Two-stroke cycle engine



Sept. 20, v1932. R L, SOUTHERN 1,878,339

TWO-STROKE CYCLE ENGINE Filed Au 26. 1929 2 Sheets-Sheet 1 INVENTOR Robert Le? Summer-4'2 p 1932- R. L. SOUTHERN 1,878,339

TWO-STROKE CYCLE ENGINE Filed Aug. 26, 1929 2 Sheets-Sheet 2 BY Q \ ATTORN EY Patented Sept. 20, 1932 barren STATES PATENT-OFFICE corner LEE seawater, "01* mm retro, camro ma essxcnoa. BY MESNE 'assicm MENTS, ro Umvrasmrrmmaheme ICOMlANY trwo-srnoxn cYcL'n ns-Inn Application filed August 26, 1929, Serial No: 388,350.

Thisinvention relates to gas engines ofthe twoestroke cycle type, my mainv object being to construct an engine of this fundamental character which will have the well organized advantages of that type as respects simplicity, considerably reduced weight per horseepower, steadiness of operation and throttling ability, and a relatively great possible power development as compared with engines of .the usual four-'tstrokeicycle type; without however .the excessive fuel con.- sumption usually .[COIlSldEIBd unavoidable,

and without using the crankcase of the en gine asthesource'of compression for the fuel mixture and which is yery inefficienhasis well recognized.- At the .sametime the advantages ofthe fourrstroke cycle zenglne as respects the thorough scavenging of the fired charge is incorporated in myenginefithe ,lack

of which in the ordinary two-stroke cycle engine cuts down the p'ossibleor theoretical power output considerably.

. Essentially these endsareattained by directing a charge offreshcoolair at a certain fixed pressure froman ante-chamber into each cylinder as the correspondingexhaust port opened and until. said port again closes; and while this air is still being .lllitIOa duced into the cylinder but after the exhaust port is closed, forcing a preineasured amount of fuel also under :very high pres- 7 sure into the ante-chamber of the-cylinder at such a point-that an intimate mingling of theair andwfuel immediately takes place be.- forethe mixture is delivered tothe cylinder.

'Thexcompression .of this miXture -by the movement of the piston the outer end of its strokepla-ces the same in the proper condi tion to be immediately fired tofgive the power] stroke to the piston;

- {As a result of this arrangement not only is l the cylinder thoroughly. scavenged with .pre-V compressed air after each firing'stroke but thecylinder and its spark plugs are kept cool and clean andthe fuel 'isjmixeld with pure cshair onl cso that the full possible ower development is assured and noneofthe power is lost by the fresh fuel mixture being cona inated by or mingling. with: the exhaust admira ly. I

These o j ts I afie mlil i byneal fr such structure and relative arrangement of parts as willfully appear by a perusal of the following specification and claims. 7

In the drawings similar characters of ref.- erence indicate corresponding parts in the v severalviewszr Fig. -1 is a fragmentary sectional elevation of my improved engine; V

Fig. 2 is a cross section taken through one of the cylinders of the engine. I j 7 Referring now more particularly to the characters of reference on the drawings, the engine comprises any desired number of cyl inders 1 having pistons 2 slidable therein which are connected by rods 3 with the crankshaft tvofthe usual ch-aracter which is jour v naled in the base 5 of theengine. Exhaust ports 6' .of suitable capacity communicate with each cylinder and are positioned to be uncouered by the piston only as the latter approaches its bottom stroke position as usual iniengines of this fundamental character,

Inwardly opening-poppet valves 7 (prefe v ably two to each cylinder) are mounted in the head of the same and are -actuated by cams r8- fixed on a horizontal cam shaft 9 extending-along the top of the engine. The

cam shaft is driven from the crankshaft at cra kshaf pee by su ta l driving. an shaft vcocaec oas a indi ated at and n such timed relation :to the movement of the piston as to Lcanse the -v;a ;lyes to be opened just ,as-the piston uncovers :the' exhaust port, Y

ut to be cl ed-a showtime aft vthe "P has ag inicov r dtli po t,and the ir is 00mpressed therein :to pressure 1 1; ex ding t a of th i ham e and manifold. 0 1c loo . cylinder and are arranged in opposed relation v just below the valves so as to be in position or more spark plugs 11 project into each to be directly affected by the sweep of air passing through said valves and into the cylinder when the valves are opened. Ignition is provided for at the proper time by a suitable ignition mechanism of a standard type, as is customary. V a y "Above the valves ofeach cylinder and com.- municating with the ports controlled thereby is a preferably horizontal and transversely extending chamber '12., On one eiid this "chamber is connected by a passage-13 with a 3' drive as shown, or in any other manner which may be found most suitable.

Also driven from the crankshaft by suitable connections is a pressureafuel pump 17 of suitable type, from which indivi'dual'leads 18 extendto spray nozzles 19 projectinginto the various chambers 12at the ends thereof opposite to the'co'nnection of the air passages 13 therewith. This pump is constantly driven while the engine is in operation. The pump .1 however is arranged to deliver the fuel under 1 pressure to the various leads only intermittently,ior'mu'ch' in the same way as an'electrical distributor controls the time j of firing of the various plugs of an ignition system. The working mechanism of the pump is of course connected to the crankshaft of the engine in such timed relation that the fuel will be delivered to the various chambers only at the exact period in the cycle ofoperations when it'is wanted.

The above features of construction are the only ones having'any direct bearing on my invention, the force feed lubricating mech anism, the exterior cooling mechanism, and

other features having nothing to do with my invention as far as the functioning ofthe csdescend.

the crankshaft the supercharger is constant-o ly'driven at 1 engine speed, this being so sential features thereof is concerned;

In operationeach piston of course functions independently of the others and there;

fore only the operation of one piston and its cooperating parts will be described:

Commencing with the beginning of the firing stroke and assuming that a compressed mixture is in the cylinder the firing of the mixture by the plugs causes the piston to With the consequent rotation'of constructed that a constant supply of air under pressure is delivered'to and maintained quently formed mixture.

in the manifold 13aand chamber 12. Such air however is not delivered to the cylinder of the fired charge. Besides the cylinder be ing cooled by the excess of air (which is of great importance), any'carbon is swept from the same, and the plugs being in the direct path ofthe inrushing air at its coolest point are cooledr and cleaned also so that they do not tend to crack or to become fouled. I have found from experiments that this airshould be admitted at an exact pressure of 20.2 pounds absolute, which pressure is necessary to properly scavenge the cylinder, as well as to give the best and most elficient working pressure of the .fuel mixture."-My; experiments'showe'd that a pressure. even a fraction above said 20.2 tended to cause preignition, while; with a. lower pressure the-scavenging was not as complete and more heat was retained in the cylinder, causing self-ignition; and less power was produced by thesubse lVhen the exhaust. ports pressure in the cylinder adjacent the same is of course considerably less than'saidpressure:of 20.2 pounds, and the valves are con sequently allowed to remain open even after the ports have-been again closed by the pis-' ton until the cylinder pressure regains said amount." t

The operation ofthe valves'is timed so that they thenimmediately close, preventing any ,possibilty of back pressure toward the supercharger developing. Between the tim'eof closing ofthel exhaust portby the piston and the time of closing of the valves (which is a-comparatively .few degrees of arcuate movement 'of the crankshaft) the fuel pump functions to deliver raw "fuel under a heavy 1 pressure into thechamber12; the operation of the pump being timed to make such delivery at the exact movement desired, as previously explained-1 Such fuel being delivered into the chamber'in opposed relation to the air} under pressure whichfis still -entering are fully open the ice the chamber, said fuel is atonce intermingled I with thisturbulently flowing air and iscarried therewith into the cylinder ina thorough- .ly mixed form. The feeding of the fu'elby the pump ceases a very short time before the valves close to permit the air to force the mixtureinto thecylinder. ,After the valves' are closed the continued upward movement of'the piston. compresses't-his mixture so that by the time the piston reaches the top of its stroke said mixture" is ready to be fired by the plugs, whereupon the piston again de scends on Titsfiring strokeand the cycle of 'operations'ab'ove described again takes place.

From the foregoing description it will be readily seen that I have produced such a dea vice as substantially fulfills the objects of the invention as set forth herein. M While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do 'not form a departure from the spirit of the,

invention, as defined by the appended claims.

Having thus described my inventionwhat I claim as new and useful and desire to secure by Letters Patent is: u

1. A two-stroke cycle gas engine includ ing a cylinder, a piston reciprocable therein, an exhaust port from the cylinder normally covered by the piston but positioned to be uncovered by the piston as the same approaches the bottom of its stroke, means operated by the movement of the piston to inject scavenging air under pressure into the cylinder during the entire period ofopening of the eX- haust port, and also for a certain period after the exhaust port is closed, and means for injecting fuel into the cylinder only during said last named period of delivery of air into the cylinder. H i

2. A two-stroke cycle gas engine including a cylinder, a piston reciprocable therein, an

exhaust port from the cylinder normally covered by the piston but positionedto be uncovered by the piston-as the same approaches the bottom of its stroke, a chamber at the head end of the cylinder, a passage connected to one end of said chamber, means for constantly forcing air under a predetermined pressure into said chamber, a fuel m take member discharging into said chamber, valve means between the chamber and the top of the cylinder, means to operate the valve means by the movement of the piston to permit such air to enter the cylinder'while the exhaust port is open and for a certain period after the same is again closed, and

fuel pump means connected to said fuel intake member to deliver fuel under pressure into the chamber only while the air is enter ing the cylinder after the exhaust port is closed. i

3. In a two cycle gas engine, a cylinder, a chamber at the head end of and communicating with the cylinder, an air intake pasa sage leading to one end'of the chamber, means to force air through said passage and into V the opposite end of the chamber, and means said chamber, a fuel intake passage leading to to force fuel through said fuel passage and into the chamber while the air is still flowing into thesame.

In testimony whereof I aflix my signature.

ROBERT LEE SOUTHERN. 

